Sustainability
5 answers on the topic of timber construction
Harald Hobacher, head of the timber engineering department, explains why wood is so effective in hybrid structures, and how it makes projects particularly Green and Lean.
1. Why are we building more with wood?
Sustainable construction is becoming more of a priority. Choosing the right building materials plays a decisive role here because they influence the entire life cycle of a building. Wood is an indigenous, renewable, and recyclable material, which makes it the ideal building material, and we use it efficiently and pragmatically for building construction projects. More and more projects are being realised using a hybrid design, where wood offers many possibilities. The same applies to stricter requirements for sound insulation and fire protection. It is therefore not surprising that ecologically sustainable solutions are being sought in public tenders and competitions. After all, public building owners need to act as role models. The choice of building material also influences the construction schedule. Timber components can be manufactured as large-format building elements – off-site – and accurately assembled on-site. This guarantees rapid construction progress.
2. What are the advantages of this building material?
Wood is very versatile. From a technical point of view, it is a top natural product in terms of its own weight to load-bearing capacity compared to conventional materials. It is easy to procure, available almost anywhere in the world, and brings a sustainable, environmentally friendly aspect to future construction methods. It is used as a supporting structure for buildings, as an insulating material due to its good insulating properties, and as sustainable façade cladding. On the scale required for multistorey, large-volume construction projects, a hybrid construction method combining timber with steel and concrete is always the most effective. It unites all the positive properties of the building materials. A good example is the completed Florido Liner, where the load-bearing structure consists of wood and concrete composite ceilings, prefabricated reinforced concrete columns, a solid reinforced concrete core, steel hybrid beams, and cross-laminated timber external walls. It was a challenging building in which PORR impressively demonstrated its expertise: we use every building material. Wood is also a competitive material. The downside of timber construction when it comes to costs compared to conventional brick and mortar construction, although they are hard to compare, is outweighed in the future thanks to greater scaling, optimisation of the building material, and standardisation, as well as socio-economic incentives
3. What would you like to build out of wood?
Since I completed my training as a civil engineer, I have been able to realise buildings made of a wide variety of construction materials. But my heart still beats for construction engineering. That’s why I would like to design and build long-span bridges made of timber or timber hybrid structures. Timber components offer very good properties in terms of fatigue behaviour, and they are already used in bridges, crane runways, and wind turbine towers. If the technical potential of wood is further researched and exploited in the future, and the rules of timber construction, such as structural wood preservation, are observed, there are very few limits.
4. How does timber construction fit in with our Green and Lean strategy?
I would say it hits the nail on the head. In addition to the sustainable aspects, it is predestined for the LEAN philosophy. Timber construction conserves resources and relies heavily on prefabrication in its industrial processes. The process must be planned and considered in advance.
5. What timber construction projects is PORR currently realising?
I would like to mention three projects: First, together with our colleagues from PORR Building Construction in Vienna, we are completing one of Austria’s largest and tallest timber buildings in the new urban development area Village im Dritten, the project Vis-a-Vis.
The eight above-ground storeys composed of a timber hybrid structure comprise 113 flats, five shops, and a nursery. We at pde Timber Engineering carried out structural optimisations, supported the planning phase, and took care of the timber construction management on site. Working shoulder to shoulder with the client Schwarzatal and the specialist planners involved, we redesigned the project in such a way that the respective material properties of wood and reinforced concrete are put to best use. The solid wood ceilings used have an exposed wooden surface. The exterior walls are supplied from Carinthia as prefabricated elements up to 12m long with a finished timber façade, ready for for installation
Second, PORR is acting as general contractor to build one of Europe’s largest timber construction projects on Vienna’s Donaukanal and Europe’s first urban neighbourhood using a timber hybrid design. The ten-storey LeopoldQuartier OFFICE building and the 253 flats in LeopoldQuartier LIVING will use a total of 6,600m3 of wood, which will store 6,600 tonnes of CO2 in the long term. This includes 20,000m2 of timber-concrete composite ceilings, 700 glulam columns, 20,000m2 of cross-laminated timber components, and 7,000m2 of timber frame exterior walls.
And third, in Vienna’s Favoriten district, PORR is constructing the B.R.I.O. fully hybrid residential building as part of the Neues Landgut urban development area. Together with our colleagues from the Vienna Building Construction department, we are carrying out the project using a newly developed serial construction method consisting of prefabricated elements, solid timber components, and prefabricated timber frame walls. The high degree of prefabricated timber and concrete elements and the use of them together enables an optimised construction process. Compared to a conventional reinforced concrete building, this saves around 20% CO2.
